The research plan proposed here is designed to further the understanding of how infant visual information processing changes with age. Specifically, 19 experiments have been proposed to test the generality of an information processing theory that has emerged from findings which have been accumulated over the past 10 years. This developmental theory assumes that infants of all ages process relational information, but that the type of relations and the type of informational units involved in those relations change with age. Dr. Cohen has repeatedly demonstrated with a variety of stimuli that infants progress from simple to more complex levels of processing relations. It is proposed to extend these earlier demonstrations by examining infants' reactions to more dynamic, realistic objects and events. In particular, it is planned to conduct an in-depth examination of three aspects of infant perception and cognition: (1) infants' perception of causal relations, (2) the effect of sound on infants' perception of causal relations, and (3) infants' perception of animacy. In these studies, developmental predictions are made concerning the ages at which infants will shift from attending to the independent features of an event to attending to the event as a meaningful whole. These predictions are based on two contrasting types of models of infant perception: an Independent Features model and a Conceptual model. The Independent Features model predicts that infants will process an event perceptually on the basis of its component features, whereas the Conceptual model predicts that infants will integrate those features and process the same event on a more abstract, holistic, conceptual basis. For example, when infants view one object collide with another, the Independent Features model predicts that infants will simply perceive the spatial and temporal features of the event. On the other hand, the Conceptual model predicts that infants will combine the spatial and temporal features and process the event as "causal." In order to study these three areas of interest and to examine these two models, three well-established designs will be used: (1) the "Switch" design which provides evidence for whether infants are processing independent features or more abstract wholes, (2) the "Feature Detection" design which provides evidence for which particular features infants are able to detect, and (3) the "Categorical Perception" design which provides evidence for how infants group objects, sounds and events. Regardless of the design, all studies will employ some version of the infant visual habituation paradigm. These studies will test the generality of Dr. Cohen's theory of information processing and perhaps help further refine it.